Carnival Sunshine completed a scheduled dry dock at Navantia Cádiz in preparation for returning to passenger operations following the pandemic shutdown. The ship underwent technical maintenance, inspections, hull and machinery work, general repairs and refurbishment of hotel and passenger areas before its transatlantic repositioning and subsequent January 2022 return to service from Charleston.

Carnival Sunshine underwent a 15-day scheduled dry dock and maintenance project at Grand Bahama Shipyard in Freeport, The Bahamas, during October 2018. The project involved substantial marine repair and maintenance work, with specialist contractor SLP Maritime reporting approximately 80,000 work-hours over the 15-day execution period. Dry Dock Logistics coordinated the movement of 317 TEUs of equipment and materials supporting the shipyard operation. The work was primarily a technical maintenance project rather than a major conversion or redesign of passenger facilities. Following completion of the shipyard period, Carnival Sunshine returned to its scheduled Caribbean cruise operations from Port Canaveral, Florida, on October 21, 2018.

Carnival Sunshine, formerly Carnival Destiny, underwent an extensive $155 million conversion at Fincantieri's Arsenale Triestino San Marco shipyard in Trieste, Italy, transforming the 1996-built vessel into a substantially redesigned cruise ship. The project involved major structural alterations, including the installation of a prefabricated forward superstructure section manufactured at Fincantieri's Monfalcone shipyard, expansion of existing upper decks and construction of 182 additional passenger cabins. All 1,321 existing staterooms were refurbished with updated furnishings, décor and flat-screen televisions. New passenger facilities included the three-level Serenity Adult-Only Retreat with a swimming pool and cascading waterfall, WaterWorks with a 334-foot waterslide, and the SportSquare recreation complex with a ropes course, miniature golf and sports facilities. Dining and entertainment additions included Guy's Burger Joint, BlueIguana Cantina, Ji Ji Asian Kitchen, Cucina del Capitano, Fahrenheit 555 Steakhouse, Havana Bar, JavaBlue Café, Alchemy Bar, RedFrog Pub and the redesigned Liquid Lounge theater and nightclub. The project also included a major atrium reconstruction, replacement of the ship's fire detection system with Autronica's AutroSafe 4 technology, installation of an auxiliary diesel generator and modifications to electrical distribution and emergency power systems. More than 3,000 workers and contractors from approximately 40 countries participated in the conversion. The original 49-day schedule was extended to accommodate additional safety improvements, and the ship departed Trieste on May 4, 2013, before beginning passenger operations as Carnival Sunshine on May 5.

Carnival Sunshine, then operating as Carnival Destiny, underwent an unscheduled propulsion repair dry dock at Grand Bahama Shipyard in Freeport, The Bahamas, from February 13–20, 2010. The vessel had experienced a propulsion system malfunction that reduced its operating speed, forcing Carnival Cruise Lines to modify several Caribbean itineraries and temporarily withdraw the ship from service. The repairs required the cancellation of two scheduled cruises departing Miami on February 13 and February 18, while three earlier voyages were modified to accommodate the ship's reduced speed. The maintenance project focused on correcting the propulsion problem rather than introducing new passenger amenities or undertaking a major interior refurbishment. Following the repairs, Carnival Destiny returned to service on February 20 with a shortened two-night Bahamas cruise to Nassau, before resuming its regular four- and five-night Caribbean itinerary schedule on February 22.